The aim of this project is the analysis of how spatial asymmetries arise in the developing egg chamber of Drosophila. Four genes (spire, cappuccino, gurken, and torpedo) which are required for the correct spatial patterning of both the egg shell and the embryo will be analyzed. Three of the genes are required in cells of the germline, wheras torpedo functions in somatic cells. The analysis focusses therefore on a stage in oogenesis when both the pattern of the egg shell and the pattern of the embryo are dependent on interactions between the different ovarian cell types. To define more precisely the role of the four genes in germline and somatic cells, new alleles and chromosomal rearrangements at the loci will be isolated, and the morphology of wildtype and mutant egg chambers will be studied in whole mounts and sectioned material. Analysis of mosaic egg chambers using torpedo, as well as dominant and recessive marker mutations, will be used to investigate the role of the follicle cells in the patterning of the egg chamber. An initial molecular analysis of spire and torpedo will be performed. This will consist of a genomic walk to the chromosomal region containing the two loci, identification of the genes, and an analysis of the spatial and temporal distribution of their products. This will allow us to develop a molecular model of patterning mechanisms acting in the egg chamber.